Electric switch.



W. n. R. MAuDIARMID.

ELECTRIC SWITOH'. APPLICATION nun mm: s, 1908.

Patented May 31, 1910.

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1). R.- MAoDIARMID. ELECTRIC swrroa.

APPLIOYATIONIFILED JUNE-3, 1908. 959,769, Patented May 31,1910.

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immu A an I 5% L FIG 12 IN VENTDR W. .D. R M'EDIARMID.

WESLEY DUNCAN RICHARD MAcDTARMID,.-OF OTTAWA, ONTARIO, CANADA, ASSIGNOROF ONE-THIRD TO HORACE CASLER DIER AND ONE-THIRD TO CLAUDE ELMERWILTSIE, BOTH OF OTTAWA, CANADA.

ELECTRIC SWITCH.

Specification of Letters Patent.

Patented May 31, acre.

Application filed June 3, 1908. Serial No. 436,331.

To all whom it may concern:

Be it known that I, WnsLnY DUNCAN RICHARD MAODIARMIB, of the city ofOttawa, Province of Ontario, Canada, have invented certain new anduseful Improvements in Electric Switches, of which the following is aspecification.

My invention relates to improvements in electric switches, particularlyof the rotating commutator type, and its objects are to eliminatesparking in such switches, and to provide a spring in connection withthe com.- mutator which will render the same absolutely safe, inoperation, and free from any liability of arcing.

Further objects are to provide improved means of attaching the cover tothe switch and to improve the binding posts and brush holders, thedifferent features of the invention being fully set forth and describedin the following-specification and accompany ing drawings.

In the drawings, Figure l is a perspective view of the switch with thecover removed. Fig. 2 is a vertical section hrough the cover in place.Fig. 3 a plan view with the cover removed. Fig. i is a vertical sectionthrough an alternative form of the invention. Fig. 5 is a verticalsection through an incandescent lamp socket with a switch manufacturedaccording to the present invention. 6 is a side view of the socket withthe cover removed. Fig. 7 is a transverse sectional view showing the pinon the de pressible member which enters the inclined groove on thereciprocative member. Fig. 8 is a perspective view of the ratchet wheelon the commutator. Fig. 9 is a perspective view of the reciprocativemember. Fig. 10 is a perspective view of the contact points on thecommutator. Fig. 11 is a transverse section through the commutator. Fig.12 is a vertical section through the switch applied to a pendant.

In the drawings, like characters of refer ence indicate correspondingparts in each figure.

lteferring, first, to the forms illustrated in Figs. 1 to 4 and 7 to 11,A. represents the base of any suitable insulating material, whichsupports the central post 10 of the switch, the said post, in theembodiment illustrated, having a reduced screw-threaded lower portion,11, which extends'through the base and is held by a nut 12 screwed onthe end of the same.

The top of the post is provided with an enlarged cylindrical portion 13on which fits the tubular depressible member B, the top 14 of whichserves as the press button for the switch. This depressible member isprevented from turning during depression, by means of a pin 15 on thecentral post extending through a slot 16 on the member. The member isretained in raised position by means of a compression spring 17 locatedwithin the same and extending between the top of the post and the top ofthe depressible member.

Mounted on the central post 10 immediately above the base, is therotatable commutator C which has a ratchet shaped periphery and hasconducting contact plates 18 and 19, located in rabbets 20 and 21 in theperiphery, and immediately at the end of the contact plates secondrabbets 22 and 23 are formed, in order that the brushes may spring clearof the contact plates, the instant they have moved past the same. Thecontact plates are electrically connected in a suitable manner, thatillustrated consisting of a base plate 24 integral with the contactplates and having a central aperture 25 which extends around the post 10leaving an annular insulating air space between.

D and E are the brushes which are formed of U-shaped strips of springmetal having their free ends bearing against the periphery of thecommutator. Their opposite ends are held in the binding posts F and G,each of which is formed by a strip of metal 26 folded on itself, andhaving the free ends attached to the spring brush by a screw 27, asuitable cylindrical recess 28 being formed in the folded end, intowhich the conducting wire'may be inserted and a suitable clampingset-screw 29 being provided extending through the folded end. One of theends of the folded strip 26 has a projecting flange 30 formed integralthereon, which is bent beneath the two ends and secured to the base A.

In order to cause rotation of the commutator on each depression of thedepressible member B, a reciprocative connecting member H is providedhaving an annular ratchet wheel 31 formed on the bottom thereof,

and thus, when the depressible member is depressed, it will cause aturning movement of the connecting member and this will be communicatedto the commutator through the cooperating ratchet wheels 31 and 32. Onrelease of the depressible member, the spring 17 will raise the sameupwardly and the pin 33' will cooperate with the slot 34: to turn thereciprocative connecting member in the reverse direction, but

, this, on account of the peculiar formation of the ratchet wheels willproduce no rotation of the commutator.

Preferably, only the two contact points are provided on the commutator,but it is evident that if desired, a greater number might be employed,and thus a three or even four pole switch provided. When only twocontact plates are provided, central intermediate rabbets 35 and 36 areprovided, into which the ends of the spring brushes are adapted to fitwhen the switch is open, as shown in Fig. 11. It may also be mentionedthat the inclination of the contact plates 18 and 19 is slightly greaterthan that of a tangent, to the periphery of the commutator at thatpoint, whereby an increased spring resistance will be ofiered by thebrushes to the initial movement of the commutator thereby causing anexcessive pressure to be exerted on the depressible memher, which, whenthe commutator once starts to move, will result in it being almostinstantaneously turned to open position.

I represents the domeshaped casing for the upper part of the switch,having the lower edge thereof adapted to take into a rabbet 37 in thebase, the said casing being provided with a central aperture 38, throughwhich the depressible member B extends. The casing is retained inposition by means of a screw-threaded member on the interior of theaperture 38 which engages the pin 15 which is lengthened for thatpurpose. In the embodiment illustrated, this screw-threaded member isformed by a spring 39 located within an annular extension 40 on .thecasing and secured thereto, and this spring, as well as forming a spirallocking means, gives acertain degree of resiliency to the lock, therebyinsuring that the casing will always be held tightly in position, andwill not work loose.

The inclined spiral groove 34: extends substantially one quarter wayaround the memher, and thus, on each depression, the coinmutator will berotated ninety degrees, and this will alternately bring the rabbets 20and 21, 35 and 36, into engagement with the end of the spring brushes,thereby alternately making and breaking the circuit between the brushes.

In the form shown in Fig. l, the compression spring 1? is omitted, and aspiral spring 41 provided extending around the shank on the inside ofthe reciprocative member, and having the upper end connected to theshank and the lower end to the reciprocative menu ber. Thus, when themember is turned, the

spring will be wound up and on release, will restore it to its originalposition. In addition to this, the spring being compressive as well asspiral, Wlll press the reciprocating member downwardly, and hold theratchet wheel 31 thereon, in resilient contact with the correspondingratchet wheel 32.

In the application of the invention to an incandescent lamp socket, asshown in Figs. 5 and 6, J represents the exterior casing of suitableconstruction, and K and L the top and bottom blocks of porcelain orother suit-- able material, connected together by uprights l2 and 43.The central post a l is supported from the upright 32 and thedepressible member 45 extends through a suitable aperture in the member43. The commutator 46 is necessarily reduced in diameter, but isotherwise constructed and arranged the same as hereinbefore described.The brushes and 48 are supported from the top and bot tom blocksrespectively, and the electrical. connections of the socket areefi'ected in the usual manner, the current passing through the brushesto the screw-threaded socket 18 on the lamp, and then, through the lampback to the central contact point 49, and from there out the otherconductor.

In the form shown in Fig. 12, the construction of the switch M itself isthe same as shown in Figs. 1 to 3 but the base 50 of the switch, issupported from the upper member 51 of a spherical casing, N, the lowermember 52 having suitable releasable engagement with the upper member,as by the screw -threading illustrated. The upper member is, as usual,provided with an aperture 53 through which the conducting cords 54 and55 extend.

A considerable advantage in the construction of my switch is the snapeffectin its action, due to the spring brushes acting together with therabbets in the armature.

It will be seen that it is impossible to partially turn the switch on oroff, as, until the brush reaches the edge of the rabbets above thecontact plate, no electrical connection is made, and if released, itwould simply, under action of the spring 1'7, return to its normalposition. In the same way, when the circuit is being broken, it isnecessary to exert an excessive pressure to overcome the resistance ofthe spring brushes, and this causes the commutator to at once swingaround to open position. It may be observed also that if the commutatorwere in closed position, and only a slight movement made, the brusheswould remain in contact with the plates until they passed the edge ofthe rabbets 22 and 23 when they would at once spring out of contact, andit 'is impossible to move them back into engaged position, withoutrotating the commutator first to closed position. It will also beobserved that the walls of the rabbets 22 and 23 extend substantiallyradially and that the peripherally extending insulating portion betweenthe rabbets and the notches 35 and 36 is considerably less in diameterthan the shortest distance between the contact plates, and so whenthebrushes have once passed the edge of the contact plates, they will atonce jump to the insulating portions of less diameter, and owing to theradial character of the wall, it will be impossible for them to beforced outwardly against the contact plates or to produce an arc.

above construction, and many apparently widely difierent embodiments ofmy invention within the scope of the appended claims could be madewithout departing from the spirit or scope thereof, it is intended thatall matter contained in these specifications and drawings shall beinterpreted as illustrative and not in a limiting sense. It is also tobe understood that the language of the following claims is intended tocover such generic and specific features of the invention hereindescribed which, as a matter of language, might be said to be includedthereby.

What I claim as my invention is:

1. In an electric switch and in combination, abase, a central postthereon, a depressible member -slidably mounted on the end of the post,means for preventing rotation of the same, a tubular reciprocatingconnecting member also rotatably mounted on the post, connecting meansextending between the depressible member and the connecting member,whereby the depression and raising of the depressible memberreciprocates the reciprocating member, a commutator mounted on the postand means for communicating the movement of the reciprocating member inone direction only to the commutator.

2. In an electric switch, and in combina- As many changes could be madein the tion,a base,a central post thereon,havin a pin outwardlyprotruding therefrom, a tu ular depressible member mounted on the top ofthe post, having a longitudinal slot 111 which the pin extends, atubular reclprocative connecting member mounted on the shaft having aninclined slot therein, a pin on the depressible member entering saidslot, a commutator and means for communicating the movement of thereciprocative member in one direction only to the commutator.

3. In an electric switch, the combination with the brushes, of a bindingpostponsisting of a strip of metal folded on itself to engage the brushbetween its outer ends, a screw extending through the inner end of thestrip adapted to clam a conducting wire inserted therein, and a. ange onone end of the folded strip bent beneath the same, by means of which thebinding post may be attached to the base. p

4. In an electric switch, the combination with the base and central postthereon, of a casing having a central aperture therein, a screw-threadedmember formed on the interior of the aperture, and a pin on the postengaging the screw-threaded member.

5. In an electric switch, the combination with the base, of a casingmounted thereon having a central aperture therein with a springsupported on the interior of the aperture, and means extending from thebase and engaging between the coils of the spring, whereby on rotationof the casing and ipring, the casing will be clamped to the ase.

6. In an electric switch, a commutator having spaced contact plates withrabbets be low the edge of each and being formed with a radiallyextending wall and notches half way between the contact plates providingperipherally extending annular insulating portions between the u peredges of the notches and the wall of the rabbets, said insulatingportions having a diameter less than the distance between the nearestportions of the contact plates and brushes engaging the commutator andadapted to engage the notches when the commutator is turned to cut offthe current.-

In witness whereof I have hereunto set my hand in the presence of twowitnesses.

WESLEY DUNCAN RICHARD MACDIARMID.

Witnesses:

RUssEL S. SMART, J. H. OLNEY.

